Anorexia in Dogs

What is anorexia?

Anorexia is a decrease or loss of appetite for food. While hunger is a physically driven, appetite is mentally driven. There are two types of anorexia: true anorexia and “pseudo-anorexia.” Both result in decreased food intake, but a dog with pseudo-anorexia wants to eat (is hungry) but can’t because of difficulty picking up, chewing, or swallowing food or some other cause (see below). Regardless of whether a dog is dealing with true or pseudo-anorexia, decreased appetite and decreased food intake are outward signs that should be taken seriously. These signs may indicate potentially life-threatening underlying conditions. Poor appetite or refusal to eat is strongly associated with illness and is a common reason for dog owners to seek veterinary care.

"Decreased appetite and decreased food intake
may indicate potentially life-threatening underlying
conditions and should be taken seriously."

What causes anorexia and pseudo-anorexia?

There are many potential explanations for decreased food consumption, and the first, most important step is to determine whether the dog has true or pseudo-anorexia. Does she want to eat but can’t, or is she truly not interested in eating? Your veterinarian will want to take a detailed history to begin to differentiate between the two conditions. Next, he or she will give your dog a thorough physical examination to try to determine the presence of an obvious physical explanation for decreased food consumption. Finally, diagnostic tests will be used to aid in uncovering a reason for decreased appetite. These may include laboratory tests such as a complete blood count (CBC) and a serum chemistry profile, electrolytes (mineral balance), radiographs (x-rays) of the chest and abdomen, ultrasound studies, and (depending on other findings), more invasive diagnostics like endoscopy.

Potential explanations for pseudo-anorexia in which a dog wants to eat but won’t or has difficulty eating include:

Stomatitis, gingivitis, or esophagitis—inflammation and pain within the tissues of the mouth and throat.

Advanced periodontal disease, which may include loose teeth.

An abscess behind the eye.

Pain in the mastication (chewing) muscles.

Pain in the temporomandibular joint (TMJ).

Salivary gland disease.

Nervous system disease affecting chewing and swallowing.

Cancer/tumors of the mouth, tongue, tonsil, or associated structures.

Pain anywhere in the body. Chronic pain is very distracting. It may interfere with appetite or with the dog’s ability to reach her food and water dishes on the floor if, for instance, she is dealing with back pain.

True anorexia can also have various causes:

Systemic disease, whether it involves infection or an organ system dysfunction, can lead to anorexia.

Psychological explanations, such as stress, altered routines, changes in the environment, or undesirable/unpalatable food.

Exposure to poisons.

Immune system imbalance/disease.

Inability to smell. Scent is an important contributor to palatability of food and appetite.

Any painful condition can suppress appetite.

Cancers of all types.

Gastrointestinal (GI) blockage.

Stomach or intestinal ulcer.

Nausea from any cause.

High environmental temperature.

Medication side effects.

How are anorexia and pseudo-anorexia treated?

"To treat decreased food intake, whether from true
anorexia or pseudo-anorexia, it is critical to identify
and correct the underlying problem."

To treat decreased food intake, whether from true anorexia or pseudo-anorexia, it is critical to identify and correct the underlying problem. That part of treatment will depend completely on what the diagnosis is. Associated or additional treatment will focus on treating/managing related symptoms. For instance, if the dog is dehydrated, then intravenous fluids may be needed. Any nausea must be eliminated. If it is appropriate, your veterinarian may prescribe a short-term appetite stimulant such as cyproheptadine or mirtazapine. If there is a mineral imbalance like low potassium, which can interfere with normal appetite, then a potassium supplement will be added. It may be useful to enhance the palatability of the dog’s food. Your veterinarian can help you with specific recommendations, but simple steps to try include:

Adding a canned formulation to the diet.

Heating food to approximately body temperature (~100°F [38°C]).

Adding a bit of low-sodium chicken, vegetable, or beef broth for flavor enhancement.

Temporarily home cooking with guidance from your veterinarian as to appropriate recipes.

Occasionally, an anorectic dog who has an underlying metabolic disorder must receive nutrients but is unwilling to eat. In these cases, it may be necessary for your veterinarian to place a feeding tube into the esophagus, stomach, or small intestine through a small incision in the skin. Feeding tubes are generally not considered heroic interventions, but they are nearly always life-saving. Food and medication can be delivered with very little stress on the dog. If the GI system is capable of digestion, it should be used, even if that means delivering food through a tube for a while. If the GI system is not working for some reason, your veterinarian may recommend what is called parenteral feeding, in which nutrition is
provided intravenously. Parenteral feeding is a specialized, complicated technique generally performed by a specialist in a referral center. Tube feeding and parenteral nutrition are most often undertaken as “bridge” procedures until the dog can eat on her own.

What is my takeaway message?

Regardless of the reason for decreased food intake, changes in eating habits and patterns warrant investigation. Lost or decreased appetite may signal something serious and may contribute to a serious consequence or outcome. Take changes in your dog’s eating behavior seriously, and get your veterinarian involved early.

This client information sheet is based on material written by: Robin Downing, DVM, CVPP, DAAPM.